Room temperature near unity spin polarization in 2D Van der Waals heterostructures

Abstract

The generation and manipulation of spin polarization at room temperature are essential for 2D van der Waals (vdW) materials-based spin-photonic and spintronic applications. However, most of the high degree polarization is achieved at cryogenic temperatures, where the spin-valley polarization lifetime is increased. Here, we report on room temperature high-spin polarization in 2D layers by reducing its carrier lifetime via the construction of vdW heterostructures. A near unity degree of polarization is observed in PbI₂ layers with the formation of type-I and type-II band aligned vdW heterostructures with monolayer WS₂ and WSe₂. We demonstrate that the spin polarization is related to the carrier lifetime and can be manipulated by the layer thickness, temperature, and excitation wavelength. We further elucidate the carrier dynamics and measure the polarization lifetime in these heterostructures. Our work provides a promising approach to achieve room temperature high-spin polarizations, which contribute to spin-photonics applications.

In two-dimensional semiconductors, light can generate spin polarisations, however this effect is typically limited to low temperatures. By combining Lead Iodide (PbI₂) with transition metal dichalcogenides (TMDCs), the authors demonstrate room temperature light induced near-unity spin polarisations.